This invention relates to a relatively low cost, disposable syringe designed to reduce or eliminate accidental needle strikes by enabling selective position control of a cartridge mounted needle from an injecting position to a retracted and locked position.
Hypodermic syringes are used for a variety of injection procedures including the delivery of medicinal drugs and anesthetics to a patient. Once the injection procedure is completed, problems can arise if the syringe is not disposed of properly and adequately. Healthcare workers are susceptible to accidental and potentially infectious needle strikes if the needle is carelessly handled or broken during disposal of the syringe after use. If an accidental needle strike does occur, a blood test is typically required to determine whether the worker has been infected. The cost of performing such tests and the loss of personnel time attendant upon such tests can be particularly damaging to a healthcare facility striving for economy and efficiency.
There are several known syringes designed to provide retraction of a syringe needle after use. In some such designs, the apparatus is designed such that the needle is retracted within the same ampoule which initially housed the medication dispensed with the syringe. In other known devices, the retraction mechanism is designed to retract the used needle within the syringe housing and lock the needle in the retracted position.
While such known designs have been found suitable in a wide variety of applications, none is compatible with a syringe using the Wyeth needle cartridge. In the Wyeth design, a single ended needle is bonded to a plastic carrier member, which in turn is secured to the ampoule containing a liquid medication. The needle passageway is in fluid communication with the interior of the ampoule, and a pliant needle cover, usually fabricated from rubber, is removably attached to the needle carrier member to seal the needle from ambient until the medication is ready to be dispensed. The needle carrier is provided with externally formed threads or ridges. Since the Wyeth needle cartridge provides a convenient supply of a variety of medications at relatively low cost, such cartridges have found wide use. However, after the medication has been dispensed from a Wyeth needle cartridge, the needle is exposed and poses a safety threat requiring special disposal procedures. Consequently, the need exists for an economical disposable syringe which is compatible with the Wyeth type of needle cartridge, and which provides safe handling and disposal for such needle cartridges after use.